This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Long Xi Yu, a senior research associate from the group of the late Prof. Ray Wu (Cornell University, Molecular Biology and genetics) is interested in the detection of free radicals in tobacco smoke. The aim of this research project is to find a treatment for cigarette filters which reduces the concentration of free radicals in the tobacco smoke and thus ameliorate harmful effects of smoking. After a number of experiments we chose for detection of free radical a spin-trapping technique using BPN (N-tert- Butil-phenylnitrone) in organic solvents. We found that the removal of water condensation from the analyzed smoke before trapping is key for obtaining reproducible quantitative results. For ESR measurements the solvents were deoxygenated. We found several natural and artificial antioxidant treatments for cigarette filters which cause substantial reduction of the free radical content in the tobacco smoke. However, upon storage of treated cigarettes the levels of free radical gradually returns to the control levels for untreated cigarettes. The work is in progress to find a durable treatment for possible commercial applications.